1. Field of the Invention
The present invention relates generally apparatus and method for providing percutaneous access to hollow body organs, tissue, and cavities. More particularly, the present invention relates to the construction and use of a dilator device which facilitates radial expansion of small diameter access punctures to create larger diameter working channels for subsequent introduction of instruments, medication, fluids, and the like.
Modern medicine frequently requires percutaneous access to hollow body organs, tissue, cavities, and the like. In the case of "least or minimally invasive" surgical procedures, such access is usually provided by inserting a suitable cannula, instrument, tube, or the like, through a small access hole. The initial access is usually created by piercing the skin and any intermediate body structures with a needle or trocar. The initial puncture, however, is usually very small so that the needle or trocar can achieve the desired penetration without excessive damage to tissue. It is therefore necessary for the initial access hole to be subsequently enlarged to provide a working channel having a sufficient diameter to permit performance of the desired medical procedure.
One common technique for achieving such enlargement relies on successively introducing one or more dilating rods having increasingly larger diameters through the puncture hole and into the body organ, tissue, or cavity. When a flexible guide wire has been introduced through the initial needle or cannula puncture, this protocol is referred to as the Seldinger technique.
While this technique is reasonably effective for placement of relatively small devices, e.g., catheters to about 6 French (F; 0.079 inch diameter), larger dilations require increasing numbers of dilator exchanges and can be extremely time consuming. Moreover, the body structures that are being penetrated frequently comprise relatively flaccid membranes or walls so that penetration with larger dilators may cause fascial detachment, i.e., the invagination and separation of the membrane or wall from surrounding tissue structures. Such problems may be exacerbated when the organ, tissue, or cavity being penetrated is diseased so that the membranes or walls are thickened or toughened and resistant to penetration by the dilator which axially engages the tissue.
One approach for preventing fascial detachment of the internal body organ or structure during the dilation process involves the use of separate anchoring instruments which are placed around the site of penetration and dilation. The technique, developed by Dr. Cope, relies on the placement of multiple separate anchors or toggles peripherally about the site of the primary puncture in order to more strongly attach the body organ to its surrounding fascia. The anchors are attached to lengths of suture which extend through the tracks defined by the separate punctures. The sutures are tensioned in order to hold the wall of the hollow organ against the fascia and subsequently secured outside the body. While this approach is generally successful, it requires a separate puncture for each anchor and the subsequent suturing of each anchor in place. The technique is therefore relatively time consuming, costly, and potentially subjects the patient to greater discomfort.
An additional problem with the use of successively larger dilators, either with or without use of the Cope anchoring technique, is the leakage of body fluids and substances through the penetration which is being enlarged While such leakage will be inhibited while each successive dilator is in place, removal of the dilator will allow the fluids from the organ, tissue or cavity being penetrated to contaminate other body structures on the puncture track. For example, percutaneous access to the gallbladder is normally achieved transhepatically since the gallbladder is partially attached to the liver. Transperitoneal access proceeds through an unattached wall of the gallbladder and increases the likelihood of bile leakage into the peritoneal. While transperitoneal access might otherwise be preferred for a number of reasons, e.g., it avoids potential damage to the liver, it is contraindicated by the difficulty in penetrating the unattached wall of the gallbladder and the greater risk of bile leakage associated with conventional dilation techniques.
For these reasons, it would be desirable to provide improved methods and apparatus for forming and enlarging percutaneous penetrations into hollow body organs, tissues, and cavities. The apparatus and methods should be suitable for enlarging percutaneous access penetrations to virtually any diameter, including very large diameters on the order of 20 F, 24 F, and larger while reducing the risk of invagination and fascial detachment of the organ, tissue, or cavity which is being penetrated. The methods should minimize any additional time and complexity required for performing an associated interventional procedure, and in particular, should avoid the need to make secondary penetrations in order to secure the body organ, tissue, or cavity to surrounding fascia. The methods should further avoid complexity and will preferably reduce the number of incremental dilations required to achieve a desired enlargement. The method should also lessen the patient discomfort associated with the procedure and should be compatible with virtually any type of interventional procedure which requires the formation of a percutaneous penetration for access to the body organ, tissue, or cavity.
2. Description of the Background Art
U.S. Pat. No. 4,738,666, describes an expandable catheter having an external sheath which is perforated to facilitate removal as the catheter is being expanded. U.S. Pat. No. 4,601,713, describes a variable diameter catheter having an inflatable retention balloon at its distal end. The catheter is introduced with an internal stylet which holds the catheter in a collapsed (reduced diameter) configuration. Removal of the stylet allows the catheter to expand. U.S. Pat. No. 4,141,364, describes an expandable endotracheal tube which is inserted in a collapsed configuration and springs back to an expanded configuration when air is introduced. Inflatable dilator apparatus are described in U.S. Pat. Nos. 4,589,868 and 2,548,602. Catheters having expandable structures are described in U.S. Pat. Nos. 4,986,830; 4,955,895; 4,896,669; 4,479,497; and 3,902,492.
U.S. Pat. No. 4,772,266, describes a dilator/sheath assembly that may be passed over an indwelling guide wire in order to enlarge an access hole, with entry of the sheath further enlarging the hole. U.S. Pat. No. 1,213,001, describes a trocar and cannula assembly which includes an intermediate tube to form a three-piece structure. U.S. Pat. No. 3,742,958, discloses a cannula having an axial slot to allow the cannula to be stripped from a working catheter which has been introduced through the cannula. U.S. Pat. Nos. 4,888,000; 4,865,593; 4,581,025; 3,545,443; and 1,248,492, each describe devices suitable for percutaneous penetration of a body cavity, blood vessel, or solid tissue. The disclosures of each of the U.S. Patents cited in this paragraph are hereby incorporated herein by reference.
Methods which rely on the percutaneous introduction of a catheter into the gallbladder and other hollow body organs are described in copending application Ser. Nos. 07/407,839; 07/529,077; and 07/551,971, the disclosures of which are incorporated herein by reference. A dilator assembly including a guide member having an anchor at its distal end is described in copending application Ser. No. 07/616,122, the disclosure of which is incorporated herein by reference.